Selective electrochemical oxidation of heteroatom compounds having both silicon and tin on the same carbon as electroauxiliaries

The selective electrochemical oxidation of heteroatom compounds having two different electro auxiliaries, i.e. silicon and tin, on the same alpha -car bon was examined. The oxidation potentials of such compounds were found to be similar to those of the corresponding compounds having only tin, indicat ing the predominant role of tin over that of silicon. The HOMO levels obtai ned by the molecular orbital calculations were consistent with the experime ntal results. The molecular orbital calculation of the cation radical sugge sts the selective cleavage of the C-Sn bond by the oxidation. Preparative e lectrochemical oxidation gave rise to selective cleavage of the C-Sn bond a nd the introduction of a nucleophile to the carbon. The C-Si bond was not a ffected at all. The product can also be further oxidized using the silyl gr oup as an electro auxiliary. The second oxidation proceeded smoothly to cle ave the C-Si bond and a second nucleophile was introduced on the same carbo n. The present study indicates the feasibility of the redox potential based selective sequential transformation using electroauxiliaries. (C) 2001 Els evier Science B.V. All rights reserved.